1. Field of the Invention
This invention relates to a chuck key holder for positioning a chuck key in spanning engagement with a drill chuck and for automatically rejecting the chuck key upon manual release of the holder.
2. Description of the Prior Art
Automatic ejection of a chuck key from spanning engagement with a drill chuck is desirable in order to prevent inadvertent rotational operation with the key still engaged with the chuck. This ejection prevents injuries that may occur by swinging of the chuck key about the chuck during its rotation.
One conventional way of ejecting chuck keys is to spring load the nose of the key which is inserted into the drill chuck hole so that manual release of the key causes the spring loading to move the nose outwardly in a resilient manner that provides the ejection of the key. However, this spring loading must be overcome by force applied to the chuck key when it is inserted into the chuck in spanning engagement for tightening or loosening a drill within the chuck. Difficulty in maintaining the meshing engagement between the key and chuck teeth can take place while concomitantly attempting to overcome the spring loading of the key nose, especially when the teeth become worn.
Holders for positioning the chuck while also providing automatic ejection thereof are disclosed by U.S. Pat. Nos. 3,174,365 and 3,728,038. These holders also automatically eject the key from the chuck upon manual release and guide the key into and out of spanning engagement with the chuck. However, the force which is applied to the chuck key during tightening and loosening of a drill must overcome the bias of the holder just like with the spring loaded nose type chuck key ejector. The same problem of maintaining the chuck in position against the spring bias is thus present with this type of holder.
U.S. Pat. No. 3,190,665 discloses a chuck key holder which does not have automatic ejection but which nevertheless positions the chuck key for movement into and of spanning engagement with the drill chuck. This is accomplished by a partially circular portion of the holder which is moved axially over the chuck and a U-shaped portion connected to the partially circular portion and having a hole in which the chuck is slidably mounted for movement toward and away from the chuck.
British Patent specification 847,385 discloses a nut spanner in which a pair of members are pivoted to each other in a scissor-like manner so that rotational operation of a nut tightener mechanism can provide tightening of a specially designed toothed nut captured between cooperable first ends of the members. Movement of second end of the members toward and away from each other provides for the release or postioning of the nut for operation of the tightening mechanism.